Hi,
I hope someone can help.
I have a 123 tune on my 1962, 3.8 mk2. It is standard apart from a classic fabs exhaust manifold and large bore system and, of course, the 123 tune. It is 8:1 compression, compression values of between 150 and 160 PSI.
I am trying to set up the advance curves and I am getting confused. The manual shows this -
I have the 40640 dizzy and the test data in the workshop manual suggests the timing should be all in at 3400 revs and there should be around 19 degrees of advance (columns 8 and 9). The manual also says that static timing should be set to 7 degrees btdc, giving total advance of 26 degrees at 3400rpm.
Am I reading this correctly? Some other applications of the 3.8, 8:1 engine have timing of up to 38 degrees all in. This is a big difference.
So, I have set the centrifugal advance to this
but I have currently got the initial static timing set to 10 rather than 7, this can be accommodated (to a degree) in the 123 settings.
The original vacuum values are 8 - 18 - 7 according to the vacuum advance unit number (column 3), and in the dizzy data in the manual, the test data is in dizzy degrees not crank degrees (columns 4 and 5).
The original vacuum values are 8 - 18 - 7 according to the vacuum advance unit number (column 3), and in the dizzy data in the manual, the test data is in dizzy degrees not crank degrees (columns 4 and 5).
So I have set the vacuum advance to this
If you convert the dizzy data for the centrifugal advance to crank degrees, you get all in at 3400 rpm of 2 x 19 + 7 = 45 degrees, far too much. Or is it? Add on 14 degrees vacuum and it is firing closer to bottom dead centre than top.
Do these settings look reasonable?
Thanks for your help.
Dave